Safety device and switch



June 12, 1923. 1,458,418

C. L. JOHNSTON ET' AL SAFETY DEVICE AND SWITCH Filed March 6, '1922 EaZ.

Patented June 12,1923'.

UNITED 'STATES 1,458,418 PATENT OFFICE.

CLARENCE L. JOHNSTON, OF OAKLAND, AND CARL H. E. FBIDEN, Ol' PIEDIONT, CALIFORNIA.

SAFETY DEVICE AND SWITCH.

To allfwlwm it 'may concern:

Be it known that we, CLARENCE L. J OHN- sToN, a citizen of the United States, and a resident of the city of Oakland, in 'the county of Alameda and State of California, and CARL M. F. FRIDEN, a subject of Sweden and a resident of Piedmont, in the county of Alameda and State of California, have invented a new and useful Safety Deviceand Switch,

of which the following is a specification.

Our invention relates to a system for use in the operation of anelectric household device, such as a ilatiron. 1t is well known that man destructive fires result from inadvertent y allowing the electric current to How through the heating elements of fiatirons while they are not 1n use. This inadvertence is quite likely to occur with an ordinary electric flatiron, since very often the person who is ironing may go to another part of the house intending to return to the iron in a short time; however, circumstances are apt to arise that re uire a considerably longer absence than anticipated. Other oc currences such as sheer forgetfulness, may also result in leaving the current on with the attendent danger of roducing a temperature at or near the atiron suiliciently high to ignite paper or fabric.- lt is one Iof the ob]ects of our invention to prevent such occurrences, and to insure the sto page of the current flow unless the househo d device is actually in use.

Another object of our invention is to provide a switch which is operated to connect a flatiron to the source of suppl by the movement of the iron over the wor and to disconnect the atiron when it is stationary in a horizontal position.

Another object of the invention is to provide a switch which operates to close the circuit through the heating element when the flatiron is stood up on end.

Another object of our invention is to provide a atiron the connections for which may be completed, while it is in position for operation, by depressing the handle toward the work.

The invention possesses other advantageous features, some of which, with the foregoing, will be set forth at len h 1n the following description where we s all outline in full one form of the invention which we have selected for illustration in the vdrawings accompanying and forming part of the present specification. In the drawings, we have shown one embodiment of our invention, but

Figure 1 is a view showing our invention applied to an electric flatiron; Y

Fig. 2 is a wiring diagram showing how the safety switch may be connected with the household device; and

3 is a detail of the fiatiron handle connection, taken from line 3-3 of Fig. 1.

in the present instance our invention is shown as applied to an electric iatiron 11, adapted to be connected to a source of electrical energy by ineens of apair of projecting contact posts 12 and 13. These posts are arranged to cooperate with the connection plug 14 in the ordinary manner. This plu M'forins a part of a flexible leadof the usua construction.

An automatic switch 15 is made a part of the iron 11. This switch is for convenience carried by the handle 16 which has a longitudinal a rture 17 for accommodating this switch. is switch may be' so constructed that it completes the connection for the flatiron when t e fiatiron is in a horizontal position only in response to the normal reciprocatlon of the iron, as in the course of ironing.

llf the iron is stationary and in the horizontal position the connection cannot be maintained. This efect is produced by using a conducting liquid, such as mercury, indicated at 18 for completing the electric circuit between the contact piece 19 and either of the other contact pieces 20 and 21. The contact piece 19 is continually immersed in the mercury 18, and as the iron is reciprocated longitudinally, the mercury splashes around the pieces 20 and 21 alternately, whereb they are placed in electrical-connection with the piece 19. This automatic switch is ar-` ranged to control the connections of the iron 11. It has been found by experience that the ordinary operation of the iron sets u wave motion in the mercury which is s cient to maintain the contacts closed enough to keep the iron properly heated. The mercury 18 is contained in aclosed tube 22 of insulating material, through which the contacts 19, 20 and 21 project, so that proper external connections may be made. The tube 22 ispreferably exhausted of air, so that injurious arcing between contacts may be avoided. For this purpose also, it is preferable to operate the iron on alternating curis suiiicient mercury within the tubel to provide electrical connection between contacts 19 and 21. The connections for the iron are in this position continuously maintained; and this arrangement is useful for initially heating the iron before ironing isy commenced. There is no danger, in this position of the iron, of the production of a dan erous temperature, because the bottom sur ace ofthe iron is exposed and radiates a. good deal of heat. The level of the'mercury is low enough, however, to clear the bottom of the contact posts 20 and 21 when the iron is stationary and horizontal.

The wiring diagram of Fig. 2 shows how the automatic switch is connected.` In order that irons already in vuse or on the market may be readily equipped with the automatic switch, it is desirable to provide external connections for the switch. In th'e present instance this is taken care of by substituting 'a post 13 of special construction for that ordinarily used. vThis post is made up of two separate 'conducting parts, an internal lug-like member 24, and an external tubeike member 25. These two parts are insulated from each other by mica or other good insulation material. The part 24 is con-v nected to the heating element 26, while the other part 25 is connected to one terminal of the switch. The other terminal of the switch is connected to the part 24 as indicated. In this way when t e plug 14 is in place, the switch 15 is in series relation with the heating elements 26. Both contact ieces 20 and 21 are connected together to crm one of the terminals of switch 15. since, as stated hereinbefore, these contact pieces are in use alternately as the iron is reciprocated. An ordinary contact post may be used from which the contact post 13 is to be made. Ordinarily, standard irons are utilized, and one of its contact posts modified in accordance with this `arrangement. It is thus rendered unnecessary to alter any of the internal connections of the iatiron.

The location of the automatic switch 15 within the handle 16 permits the use of the handle itself for operating the switch. For this purpose the handle 16 mgy be pivotally supported at 27 on the han e supporting frame j28. By pressing the handle downward, the tube 22 is 'tilted suiiiciently to connectA contact pieces 19 and -20v continuously. In order to keep the handle in its horizontal position while no pressure is exerted upon it, a spring 29 is located in the arm 30 of frame 28, exerting a pressure against the shank of a screw 31 fixed to the handle 16. This shank plays Within a slot 32 located in the arm 30, as most clearly shown in Fi 3. The spring 29 is made strong enoug so that only u on a substantial pressure on handle 16 is t e tube 22 tilted sufiiciently to provide a closed circuit. The control of the circuit is thus accomplished either by the pressure of the hand grasping the iron, or by the movement of the iron itself.

It is of course to lbe understood that the iron and the switch may be arranged to be operated only by one of the two modes of operation, and not by both. For many purposes it may be better to leave the control of the switch solely to the reciprocation of the iron. Under such circumstances the handle 16 is non-pivotally1 attached to the fra-me 28.

It is evident that our invention may be applied to other electrically operated (levices, Such as corn poppers, where it becomes unnecessary or dangerous to maintain the connection if the device remains stationary.

We claim:

1. In combination, an electrically heated device, and a switch operative by the operative movement of the device to close the circuit for the device.

2. In combination, an electric atiron, means for connecting the atiron to a source of electrical ener and a switch responsive to the operative movement of the latiron whereby it acts to disconnect the fiatiron when 1t is in operative 'position but stationary.

3. In combination, an electric fiatiron, contacts controlling the {latiron circuit, and a liquid conductor responsive to the operative movement of the latiron for connecting the contacts of the flatiron.

4. In combination, an electric atiron, a

.hollow ytube arranged to be movable with the latiron, contacts projecting within the tube, and a li uid conductor in the tube, arranged to comp ete the connections for the flatiron through the contacts upon operative movement of the flatiron.

5. In combination, an electrically heated latiron and a switch arranged to automatically open the electric circuit of the iron when the iron is at rest in a horizontal position and to close said circuit by the movement of the flatiron.

6. In combination, an electrically heated ilatiron, and a switch arranged to automatically open the electric circuit of the iron when it is brought to rest in the horizontal position and'to close the circuit when the iron is stoodl on end.

7. In combination, an electric liatiron, a

`'hollow tube movable with the iatiron, and

lll

contacts controlling the atiron circuit projecting into the tube, said tube holding a liquid conductor arran ed to splash about the contacts and comp ete the circuit for tlfie iiatiron upon operative movement thereo 8. In an electric atiron, a hollow pivotally supported handle, a tube located within the handle and adapted to hold a liquid conductor, and contacts within the tube arranged tocontrol the circuit of the flatiron upon pivotal movement of the handle.

9. In an electric flatiron, a hollow handle, contacts within the handle controlling the circuit of the flatiron, and ali uid conductor lwithin the handle arrange I to connect the contacts upon longitudinal movement of the flatiron.

10. In an electric llatiron, a hollow handle and a switch controlling the circuit `for the atiron located within the handle comprising a hollow tube, contacts projecting within the tube, and a liquid conductor within the tube, the varrangement being such that the liquid conductor connects the contacts upon movement of the iatiron in a longitud-inal direction.

11. A controlling. switch for an electrically operated device having a handle, como prising a pair of contacts, and a Huid conductor for connecting the contacts to complete the electrical circuit for said device by a wave'motion of the fluid conductor upon an operative movement of the device.

12. An electrically heated device, comprising a handle and closed tube carried by the handle, contacts therefor, and a fluid conductor in the tube arran d to complete the electrical circuit to sai I heated device in response to. a wave motion of' said Huid caused by the operative movement of the device. v

13. In an electrically heated instrument, means for connecting the instrument to a source of electrical supply, and a switch responsive to the operative movement of the device to permit the flow of electrical current to said device.

14. In an electric flatiron, a container movable with the flatiron, a contact at each end of the container and near the top thereof said contacts being disposed in a line substantially parallel to the main longitudinal axis of the iatiron, another contact between the pair before mentioned and disposed near the bottom of the container, and a liquid conductor in said container arranged to connect either of the pair of contacts with the lower one only upon longitudinal movement of the iron.

In testimony whereof, we have hereunto set our hands.

CLARENCE L. JOHNSTON. CARL M. F. FRIDEN. 

